Technology
IBM integrates Arm instructions into next-generation z/Architecture
The company's hardware engineers detailed the Dual-ISA design at the Hot Chips 2026 conference.
The short version
- IBM has developed a dual-instruction set architecture (Dual-ISA) for its next-generation z/Architecture mainframe processors, allowing them to run both native z/Architecture and Arm instruction sets.
- The integration is aimed at easing large-scale software consolidation and allowing clients to deploy the rapidly growing Arm software ecosystem closer to mission-critical mainframe data.
- The hardware automatically handles translation challenges, such as endianness swapping and memory ordering, while reusing major core structures like caches and register files.
Key facts
- IBM revealed its next-generation z/Architecture design supporting both native and Arm instruction sets at the Hot Chips 2026 conference.[Hacker News]
- The processor's decode pipeline features separate decoders for each instruction set, but shares major structures like translation lookaside buffers, caches, and physical register files.[Hacker News]
- Endianness swapping between the big-endian z/Architecture and little-endian Arm is managed automatically in the hardware's load-store unit.[Hacker News]
- The core remains strongly ordered, meaning Arm's weak-ordering behaviors and Total Store Ordering (TSO) features do not alter the hardware's execution flow.[Hacker News]
- IBM executives stated they have no business case to integrate the Power architecture into mainframes, as Power and Mainframe systems serve distinct market lanes.[Hacker News]
- To address reliability concerns with High Bandwidth Memory (HBM) on its next-generation Spyre chips, IBM is utilizing matured HBM technology, running it below maximum speeds, and using rigorous manufacturing tests like high-temperature processor burn-in.[Hacker News]